DESCRIPTION: Human cytomegalovirus (HCMV) infection is the major cause of birth defects in the U.S. and the primary cause of morbidity and mortality in immunosuppressed solid organ and allogeneic stem cell transplant recipients. Mucosal immunization is considered the most effective approach to treat HCMV but is limited, in large part, by the absence of clinically viable mucosal adjuvants that generate the necessary long-term mucosal and systemic immune responses. Our preliminary data show that intranasal (IN) administration of a peptide vaccine based on the novel adjuvant EP67 generates long-term mucosal and systemic CTL that decrease productive CMV infection in the salivary glands and lungs after sublethal intranasal challenge in a murine model of CMV. Our long- term goal is to develop efficacious vaccines against HCMV for clinical use. The overall objective of this application is to demonstrate that EP67-based targeted mucosal vaccines are likely to protect against primary mucosal infection with HCMV. Our central hypothesis is that encapsulating protective CMV proteins in nanoparticles surface-modified with EP67 increases the generation of long-term mucosal and systemic immune responses required to protect against primary mucosal infection with CMV in an outbred population and within the context of the human immune system. The rationale for this work is that it is an important first step toward the commercial development of an EP67-based mucosal vaccine against HCMV. The central hypothesis will be tested through the following Specific Aims: (SA1) Identify candidate EP67-based C5aR-targeted nanoparticles for mucosal immunization. Our working hypothesis is that nanoparticle diameter, rate of encapsulated protein release, length of EP67 linker, and level of EP67 modification affect the generation of long-term mucosal and systemic immune responses against encapsulated protein after IN administration. (SA2) Generate long-term protective immune responses required to protect an outbred population against primary mucosal infection with CMV. Our working hypothesis is that modifying the nanoparticle surface with EP67 increases the generation of long-term mucosal and systemic immune responses against encapsulated CMV proteins after IN administration that protect an outbred population against primary mucosal infection with CMV. (SA3) Generate long-term mucosal and systemic immune responses in a humanized immune system that are required to protect against primary mucosal infection with HCMV. Our working hypothesis is that encapsulating protective HCMV proteins in biodegradable nanoparticles surface-modified with EP67 increases the generation of long-term mucosal and systemic immune responses after IN administration in a humanized immune system that are required for protection against primary mucosal infection with HCMV. Our contribution is to demonstrate that an EP67-based C5aR-targeted mucosal vaccine against protective HCMV proteins is likely to provide long- term protection against primary mucosal infection with HCMV.